Support additive animations on CSS property transform

third_party/WebKit/Source/core/animation/CSSTransformInterpolationType.h

Index: third_party/WebKit/Source/core/animation/CSSTransformInterpolationType.h
diff --git a/third_party/WebKit/Source/core/animation/CSSTransformInterpolationType.h b/third_party/WebKit/Source/core/animation/CSSTransformInterpolationType.h
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index 0000000000000000000000000000000000000000..984aac8dec481ecc094fafa710b630a7bcec5594
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+++ b/third_party/WebKit/Source/core/animation/CSSTransformInterpolationType.h
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+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CSSTransformInterpolationType_h
+#define CSSTransformInterpolationType_h
+
+#include "core/animation/CSSInterpolationType.h"
+
+namespace blink {
+
+class CSSTransformInterpolationType : public CSSInterpolationType {
+public:
+    CSSTransformInterpolationType(CSSPropertyID property)
+        : CSSInterpolationType(property)
+    {
+        ASSERT(property == CSSPropertyTransform);
+    }
+
+    InterpolationValue maybeConvertUnderlyingValue(const InterpolationEnvironment&) const final;
+    InterpolationValue maybeConvertSingle(const PropertySpecificKeyframe&, const InterpolationEnvironment&, const InterpolationValue& underlying, ConversionCheckers&) const final;
+    PairwiseInterpolationValue mergeSingleConversions(InterpolationValue&& start, InterpolationValue&& end) const final;
+    void composite(UnderlyingValueOwner&, double underlyingFraction, const InterpolationValue&, double interpolationFraction) const final;
+    void apply(const InterpolableValue&, const NonInterpolableValue*, InterpolationEnvironment&) const final;
+
+private:
+    InterpolationValue maybeConvertNeutral(const InterpolationValue& underlying, ConversionCheckers&) const final;
+    InterpolationValue maybeConvertInitial(const StyleResolverState&) const final;
+    InterpolationValue maybeConvertInherit(const StyleResolverState&, ConversionCheckers&) const final;
+    InterpolationValue maybeConvertValue(const CSSValue&, const StyleResolverState&, ConversionCheckers&) const final;
+};
+
+} // namespace blink
+
+#endif // CSSTransformInterpolationType_h